JP2014231748A - Exhaust gas purification device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust gas purification device miniaturized in the whole shape of the device while utilizing performance of an SCR catalyst in maximum.SOLUTION: An exhaust gas purification device includes a first exhaust gas purification device 2 in which a front stage oxidation catalyst 21 and a DPF 22 are arranged in series, a second exhaust gas purification device 3 in which two SCR catalyst devices 5 respectively configured by arranging an SCR catalyst 51 and a rear stage oxidation catalyst 52 at a downstream side, in series, are arranged in parallel with each other, and an axis CL2 of each of the SCR catalyst devices arranged in parallel is orthogonal to an axis CL1 of the first exhaust gas purification device 2, and which has an inlet connecting portion 31 for connecting second inlet chambers 53 of two SCR catalyst devices 5, a communication pipe 7 for communicating a first outlet chamber 24 and the inlet connecting portion 31 of the first exhaust gas purification device 2, and a reducer addition nozzle disposed at an upstream portion of an exhaust gas flow channel of the communication pipe 7.

Description

  The present invention relates to an exhaust gas purification device for an internal combustion engine, and more particularly to an exhaust gas purification device that removes nitrogen oxides contained in exhaust gas.

The exhaust system of a diesel engine (hereinafter referred to as “engine”), which is an internal combustion engine, contains diesel exhaust particulates (hereinafter referred to as “PM (Particulate Matter)”) that are contained in exhaust gas discharged from the engine and are harmful substances. And nitrogen oxide (hereinafter referred to as NOx), and PM is supplemented by a diesel particulate filter (hereinafter referred to as “DPF (Diesel Particulate Filter)”). The exhaust gas purified by DPF is subjected to a reduction reaction on a selective reduction catalyst that reacts NOx contained in the exhaust gas with a reducing agent (hereinafter referred to as “SCR catalyst (Selective Catalytic Reduction)”), and the NOx emission concentration Those in which the above is reduced have been widely put into practical use.
The effectiveness of ammonia (NH ₃ ), which is used as a reducing agent, is known, but there is a problem in safety when ammonia is transported on a transportation vehicle such as an automobile. Is stored in a urea water tank and is used as a reducing agent by injecting urea water into the exhaust gas from the urea water tank.
Further, on the upstream side of the DPF, a pre-stage oxidation catalyst that oxidizes NO → NO2 (2NO + O2 → 2NO2) is disposed in the SCR catalyst in order to improve the NOx purification rate.
Further, a downstream oxidation catalyst that renders NH3 slipped by the SCR catalyst harmless is disposed at a downstream side of the SCR catalyst.

Therefore, the front-stage oxidation catalyst disposed on the upstream side of the DPF, the DPF, the SCR catalyst, and the rear-stage oxidation catalyst disposed on the downstream side of the SCR catalyst must be disposed in series.
Further, urea water is added (sprayed) to the exhaust gas that has passed through the DPF, but before the exhaust gas reaches the SCR catalyst, the urea water (mist state) and the exhaust gas need to be sufficiently mixed.
For this reason, the length of the exhaust gas purification device has been increased, and there has been a problem in mountability to vehicles.

Patent document 1 is disclosed as a related prior art.
According to Patent Document 1, an exhaust gas purifying apparatus for an engine includes a first cylindrical case in which a front-stage DOC (front-stage oxidation catalyst) and a DPF are stored in order from one end side, and an SCR catalyst and a rear-stage oxidation catalyst in order from one end side. A second cylindrical case to be housed, wherein the first cylindrical case and the second cylindrical case are arranged in parallel, and one end side of the first cylindrical case and the second cylinder The other end of the first cylindrical case and the one end of the second cylindrical case are connected to each other by a connecting pipe. A technical disclosure is provided in which a reducing agent supply nozzle is provided on the upstream side.
By adopting such a structure, the distance between the urea water addition nozzle and the SCR catalyst is increased, and the entire apparatus is prevented from being elongated.

JP 2009-167806 A

However, it is necessary to increase the capacity of the SCR catalyst in order to respond to stricter exhaust gas regulations and improve fuel efficiency in the future.
On the other hand, there are regulations on the form of the vehicle, the outer dimensions of the vehicle traveling on the public road, and the like, and there are restrictions on the layout for mounting the exhaust gas purification device on the vehicle.
In the case of Patent Document 1, when the reduction capacity of the SCR catalyst is increased, the SCR catalyst becomes longer. Depending on the form of the mounted vehicle, the specified size of the vehicle may be exceeded, and there may be cases where the vehicle cannot travel on public roads.
Furthermore, when the SCR catalyst is simply lengthened, the temperature of the exhaust gas decreases toward the downstream side of the catalyst, the reactivity of the catalyst becomes worse, the catalyst capacity needs to be increased, and the mountability to the vehicle is deteriorated. In addition, there is a problem such as an increase in cost by increasing the catalyst capacity.

  Accordingly, the present invention has been made in view of such problems, and an object of the present invention is to provide an exhaust gas purifying apparatus in which the entire shape of the apparatus is made compact while making the performance of the SCR catalyst maximally usable.

The present invention achieves such an object, and is an exhaust gas purification device interposed in an exhaust system passage of an internal combustion engine,
A first exhaust gas purification device in which a front stage oxidation catalyst and a diesel particulate filter are arranged in series on the downstream side of the front stage oxidation catalyst, and an axis extending in the vehicle longitudinal direction;
A plurality of SCRs arranged downstream of the first exhaust gas purification device in the exhaust system and having a selective reduction SCR catalyst and a downstream oxidation catalyst arranged in series downstream of the selective reduction SCR catalyst. The catalyst devices are arranged in parallel, and the axes of the SCR catalyst devices arranged in parallel are arranged substantially perpendicular to the axis of the first exhaust gas purification device, and the plurality of SCR catalyst devices A second exhaust gas purification device having an inlet connection portion for connecting the respective exhaust gas inflow portions;
A communication pipe for connecting the exhaust gas outflow part of the first exhaust gas purification device and the inlet connection part to circulate the exhaust gas inside;
It is possible to provide an exhaust gas purification apparatus comprising a reducing agent addition nozzle disposed in the communication pipe and spraying a reducing agent on the exhaust gas flowing through the communication pipe.

In this invention, since the axis of each SCR catalyst device of the second exhaust gas purification device is arranged so as to be perpendicular to the axis of the first exhaust gas device (arranged in the vehicle longitudinal direction), the second exhaust gas purification device The longitudinal dimension of the vehicle can be reduced, the overall shape of the exhaust gas device can be made compact, and mounting on a vehicle and the size and weight of the entire device can be reduced.
Furthermore, by arranging the two SCR catalyst devices of the second exhaust gas purification device in parallel, the contact area between the exhaust gas and the SCR catalyst inlet is increased, and the added urea water can be utilized to the maximum extent. The volume can be reduced to the minimum necessary size, and the cost of the catalyst can be reduced.
Also, by arranging the SCR catalyst device of the second exhaust gas purification device in parallel, the passage cross-sectional area when the exhaust gas passes through the SCR catalyst device becomes large, so the flow resistance of the exhaust gas is made lower than when arranged in series. As a result, the output is improved and the fuel consumption can be improved as the exhaust resistance of the internal combustion engine decreases.

  In the present invention, preferably, the reducing agent addition nozzle is a joint portion between an outer peripheral wall of the outflow portion of the first exhaust gas purification device and the communication pipe, and is disposed at an end of the communication pipe. It is good to have.

By adopting such a configuration, the reducing agent addition nozzle is disposed at the upstream end of the exhaust system passage of the communication pipe, so that the reducing agent is sprayed from the reducing agent addition nozzle to the SCR catalyst device. By increasing the distance, the reducing agent is easily dispersed evenly in the exhaust gas, and the efficiency of the reducing action in the SCR catalyst can be improved.
Furthermore, since the reducing agent addition nozzle is disposed in the communication pipe, it is possible to prevent the reducing agent attached to the inner wall of the communication pipe from being carried to the SCR catalyst side by the exhaust gas and staying in the communication pipe.

  In the present invention, preferably, the inlet connecting portion may be provided with a diversion guide portion that allows the exhaust gas from the communication pipe to uniformly flow into each of the exhaust gas inflow portions of the plurality of SCR catalyst devices.

  By adopting such a configuration, the exhaust gas containing the reducing agent is evenly introduced into the SCR catalyst device arranged in parallel by the diversion guide portion, so that the purification efficiency can be improved.

  Preferably, in the present invention, the plurality of the SCR catalyst devices and the communication pipes arranged in parallel have a vehicle front-rear direction external dimension in a front-rear direction dimension of the first exhaust gas purification apparatus in a plan view when mounted on the vehicle. It is good to arrange | position so that it may become substantially equivalent.

  By adopting such a configuration, the exhaust gas purification device can be used in common with a vehicle having a long wheelbase (WB) even in a vehicle having a short wheelbase (WB) by arranging the exhaust gas purification device in a compact shape. It is possible to reduce the cost.

  In the present invention, it is preferable that the plurality of SCR catalyst devices arranged in parallel be displaced in the vehicle vertical direction.

By adopting such a configuration, the exhaust gas purifying apparatus adds a tractor-specific device to a tractor with a short wheelbase (WB) in addition to a large number of traveling devices similar to a vehicle with a long wheelbase (WB). Even when it is mounted, it can be shared with a vehicle having a long wheelbase (WB), and the cost can be reduced.
Furthermore, the two SCR catalyst devices can be displaced in the vehicle up-down direction to shorten the vehicle front-rear direction external dimensions, so that the travel device mounting layout can be afforded,
The mounting structure of each device on the vehicle body becomes a simple mounting structure, and the reliability of each device can be improved.

Preferably, in the invention of the present application, the vehicle includes a chassis frame having a pair of left and right side frames extending in the vehicle front-rear direction and having an interval in the vehicle width direction at the center in the vehicle width direction.
The first exhaust gas purification device may be disposed between the pair of left and right side frames, and the second exhaust gas purification device may be disposed outside the side frames in the vehicle width direction.

By adopting such a configuration, the maximum size in the vehicle width direction of a vehicle traveling on a public road is regulated by laws and regulations.
Therefore, by disposing the first exhaust gas purification device between the side frames, it is possible to increase the axial dimension of the second exhaust gas purification device, and it is possible to increase the reduction capacity of the SCR catalyst device.

  In the present invention, preferably, exhaust gas pipes are respectively disposed in the exhaust gas outflow portions of the plurality of SCR catalyst devices.

  With such a configuration, exhaust pipes are provided in the exhaust gas outflow portions of the plurality of SCR catalyst devices, respectively, so that it is possible to prevent the other exhaust interference in the exhaust gas outflow portions of each other, and the exhaust gas circulation Since the resistance is suppressed and the exhaust resistance of the internal combustion engine is reduced, the output is improved and the fuel consumption can be improved.

  ADVANTAGE OF THE INVENTION According to this invention, the exhaust gas purification apparatus which made the whole apparatus shape compact can be provided, making the performance of an SCR catalyst possible to the maximum.

1 is a schematic configuration diagram of an exhaust gas purification apparatus according to a first embodiment of the present invention. FIG. 2 shows a side view of FIG. 1. The expanded block diagram of the 2nd exhaust gas purification apparatus of this invention is shown. The schematic block diagram of the exhaust gas purification apparatus concerning 2nd Embodiment of this invention is shown. The schematic block diagram of the exhaust gas purification apparatus concerning 2nd Embodiment of this invention is shown.

Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings.
However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention only to specific examples unless otherwise specifically described. Only.
In the description, the vertical direction (gravity direction) and the front / rear / left / right direction are described with reference to the state of sitting in the driver's seat.

(First embodiment)
FIG. 1 is a plan view of a schematic configuration of an exhaust gas purifying apparatus according to a first embodiment of the present invention, and FIG. 2 is a side view of the vehicle vehicle width direction in FIG.
1 shows the whole structure of the exhaust gas purification apparatus.
The exhaust gas purification apparatus 1 includes a front-stage oxidation catalyst 21 into which exhaust gas discharged from a diesel engine (hereinafter referred to as an engine), which is an internal combustion engine mounted on a chassis frame 8 of a vehicle, and diesel particulates (hereinafter referred to as PM (Particulate)). A first exhaust gas purification device 2 having a DPF (Diesel Particulate Filter) 22 that captures (referred to as “Matter”), and a urea gas that is a reducing agent and is disposed downstream of the first exhaust gas purification device 2 Two SCR catalyst devices 5 having a SCR catalyst (Selective Catalytic Reduction) 51 for reducing NOx in exhaust gas and a post-stage oxidation catalyst 52 for purifying ammonia (NH 3) slipped by the SCR catalyst 51 are arranged in parallel. And an inlet connection that is a connecting part that introduces exhaust gas into the second inlet chamber 53 that is an exhaust gas inflow part of each of the two SCR catalyst devices 5. The second exhaust gas purification device 3 having the portion 31, the first outlet chamber 24, which is an exhaust gas outflow portion on the downstream side of the first exhaust gas purification device 2, and the inlet connection portion 31 are connected to communicate the exhaust gas inside. The communication pipe 7 and a urea water addition nozzle 9 disposed in the upstream part of the exhaust gas system of the communication pipe 7 are configured.

The exhaust gas purification device 1 is mounted on a chassis frame 8 of a vehicle.
The chassis frame 8 extends between the pair of left and right side frames LH81, RH82 and the pair of left and right side frames LH81, RH82 extending in the vehicle front-rear direction and spaced in the vehicle width direction at the vehicle width direction intermediate portion of the vehicle. The both ends are fixed to a pair of left and right side frames LH81 and RH82 and are formed in a ladder shape with a plurality of cross members 83 arranged at intervals in the vehicle front-rear direction. ing.

The first exhaust gas purification device 2 is arranged on the side frame RH82 side between the pair of left and right side frames LH81 and RH82 along the axis of the first exhaust gas purification device 2 along the vehicle longitudinal direction.
In the present embodiment, the first exhaust gas purification device 2 is mounted on the side frame RH82 side, but may be mounted on the side frame LH81.
In the first exhaust gas purification device 2, the first inlet chamber 23, which is an exhaust gas inflow portion into which exhaust gas from the engine flows, sequentially from the upstream side of the exhaust system path, the upstream oxidation catalyst 21, and the upstream oxidation catalyst 21 are spaced apart. And a first outlet chamber 24 which is an exhaust gas outflow portion.
The first inlet chamber 23 has a conical shape that is expanded from the exhaust gas inlet 23a toward the front-stage oxidation catalyst 21 so that the exhaust gas is evenly distributed with respect to the front surface of the front-stage oxidation catalyst 21. Is formed.
The first outlet chamber 24 has a space capacity that suppresses the flow resistance of the exhaust gas that has passed through the DPF 22, and is provided with a discharge port 24 a that opens in a direction substantially perpendicular to the axis CL 1 of the first exhaust gas purification device 2. .

Moreover, the following effects can be acquired by arrange | positioning the 1st exhaust gas purification apparatus 2 between a pair of left and right side frames LH81 and RH82.
That is, the maximum size in the vehicle width direction of a vehicle traveling on a public road is regulated by laws and regulations.
Therefore, by disposing the first exhaust gas purification device 2 between the side frames LH81 and RH82, the dimension of the second exhaust gas purification device 5 in the direction of the axis CL2 (the vehicle width direction size) can be increased. When the regulations are strengthened, the capacity of the SCR catalyst device can be increased.

In the SCR catalyst 51, the pre-stage oxidation catalyst 21 is oxidized from NO → NO2 (2NO + O2 → 2NO2) in order to improve the NOx purification rate.
Further, the front-stage oxidation catalyst 21 reduces PM by oxidizing the exhaust gas during normal operation, and continuously burns and reduces the PM collected by the filter by the action of NO2 generated at this time.
When a predetermined amount of PM is deposited on the filter, the added HC is burned to maintain the temperature of the filter at a high temperature, and the deposited PM is burned.
Further, the DPF 22 has a filter function for capturing unburned fine substances (hereinafter referred to as PM) in the exhaust gas.

As shown in FIG. 3, the second exhaust gas purification device 3 is disposed outside the side frame RH82 in the vehicle width direction.
The second exhaust gas purification device 3 includes, in order from the upstream side of the exhaust system path, a second inlet chamber 53 that is an exhaust gas inflow portion, an SCR catalyst 51, a rear-stage oxidation catalyst 52 that is spaced from the SCR catalyst 51, and an exhaust gas outflow. Two SCR catalyst devices 5 and 5 having a second outlet chamber 54 as a part are configured in parallel to the exhaust system path.
The two SCR catalyst devices 5 and the axis CL2 of each of the five SCR catalyst devices 5 are arranged substantially perpendicular to the axis CL1 of the first exhaust gas purification device 2.
Furthermore, it has the distance L3 between the axis lines CL2 in the plan view of the two SCR catalyst devices 5 and 5 and the communication pipe 7, and the outer dimension L2 in the front-rear direction is the outer dimension L1 in the axis direction of the first exhaust gas purification device 2. They are arranged to be substantially the same or smaller.
By doing so, the overall shape of the exhaust gas purification device 2 can be made compact, and even a vehicle with a short wheel base (WB) can be shared with a vehicle with a long wheel base (WB).

The SCR catalyst device 5 reduces NOx by ammonia generated from urea water added to the exhaust gas.
Further, the post-stage oxidation catalyst suppresses the discharge of NH3 due to the oxidation action when NH3 (ammonia) becomes excessive without being consumed by the SCR catalyst.

Further, the second exhaust gas purification device 3 is connected to the second inlet chambers 53 and 53 of the two SCR catalyst devices 5 and 5, and introduces exhaust gas from the communication pipe 7 into the second inlet chambers 53 and 53. The inlet connection part 31 and the 2nd exit chambers 54 and 54 which are the waste gas outflow parts from which the waste gas which passed the back | latter stage oxidation catalysts 52 and 52 flow out are provided.
The inlet connecting portion 31 includes diversion guide portions 31b and 31b that allow exhaust gas containing atomized urea water flowing through a communication pipe 7 to be described later to uniformly flow into the two SCR catalyst devices 5 and 5. Is formed.
The diversion guide portions 31b and 31b have a first top portion 31a at a position facing the opening center CP of the inlet portion 31c of the inlet connecting portion 31 continuous with the downstream end portion of the cylindrical communication pipe 7. Cylindrical diversion guide portions 31b and 31b formed in an arc shape connected to the second inlet chambers 53 and 53 from the top portion 31a are formed in a bifurcated shape.
Since the exhaust gas containing the reducing agent is evenly introduced into the two SCR catalyst devices 5 arranged in parallel by the diversion guide part 31, it is possible to improve the purification efficiency.

The exhaust gas purified by the SCR catalysts 51 and the rear oxidation catalyst 52 of the two SCR catalyst devices 5 and 5 of the second exhaust gas purification device 3 flows into the second outlet chambers 54 and 54.
The second outlet chambers 54 and 54 are provided with a discharge connecting portion 32 that connects the respective second outlet chambers 54 and 54. The exhaust connection portion 32 is connected to an exhaust pipe 35 that exhausts exhaust gas toward the outside of the vehicle.
The discharge connecting portion 32 is formed with discharge guide portions 32b and 32b that allow the exhaust gas flowing into the second outlet chambers 54 and 54 to smoothly flow to the exhaust pipe 35 side.
The discharge guide portions 32b and 32b have a second top portion 32a at a position facing the opening center CP2 of the exhaust system path upstream side end portion 35a of the cylindrical exhaust pipe 35, and the second top portions 32a are connected to the second top portions 32a. Cylindrical discharge guide portions 32b, 32b formed in an arc shape connected to the outlet chambers 54, 54 are formed in a bifurcated shape.
Purified exhaust gas smoothly flows to the exhaust pipe 35 side by the discharge guide portion 32b, suppresses exhaust resistance, improves the output of the engine, and provides a fuel efficiency improvement effect.

A communication pipe 7 for introducing the exhaust gas flowing into the first outlet chamber 24 into the second exhaust gas purification apparatus 3 is disposed between the first exhaust gas purification apparatus 2 and the inlet connection pipe 31.
In the communication pipe 7, the upstream end 7 a of the communication pipe 7 is joined to the outer peripheral edge of the discharge opening 24 a of the first outlet chamber 24.
On the other hand, in the communication pipe 7, the downstream edge 7 b of the communication pipe 7 is connected to the inlet portion 31 c of the inlet connection portion 31.
Further, the communication pipe 7 extends substantially in parallel with the axis CL2 of the two SCR catalyst devices 5 and 5 of the second exhaust gas purification device 3 from the discharge opening 24a, and extends linearly. In the vicinity of the outermost portion (vehicle width direction) of the SCR, it is bent at a substantially right angle with respect to the axis CL2, and is further bent in the direction of the axis CL2 at the intermediate portion between the two SCR catalyst devices 5, 5. Yes.

The communication pipe 7 includes urea water which is a connecting part between the communication pipe 7 and the outer wall of the first outlet chamber 24 and which is a reducing agent addition nozzle that sprays urea water in the form of a spray onto the end 7 a of the communication pipe 7. An addition nozzle 9 is arranged.
A reducing agent (urea water) is supplied to the urea water addition nozzle 9 by a reducing agent injection device (not shown).
By doing in this way, it becomes easy to disperse | distribute a reducing agent in exhaust gas uniformly by lengthening the distance to the SCR catalyst apparatus 5 after a reducing agent is sprayed from the urea water addition nozzle 9, and in the SCR catalyst. The efficiency of the reducing action can be improved.
Furthermore, since the urea water addition nozzle 9 is disposed in the communication pipe 7, it is possible to prevent the reducing agent adhering to the inner wall of the communication pipe 7 from being carried to the SCR catalyst side by exhaust gas and staying in the communication pipe.

The flow of exhaust gas will be described.
Exhaust gas from the engine mounted on the front portion of the chassis frame 8 is introduced from the exhaust gas inlet 23a of the first exhaust gas purification device 2 into the first inlet chamber 23 and flows to the front oxidation catalyst 21 while diffusing.
In the pre-stage oxidation catalyst 21, oxidation is performed from NO to NO 2 in the exhaust gas (2NO + O 2 → 2NO 2).
Thereafter, the particulate matter (PM) is filtered by the DPF 22 and flows out into the first outlet chamber 24.
The exhaust gas in the first outlet chamber 24 is introduced into the communication pipe 7, added with the sprayed urea water from the urea water addition nozzle 9, and flows to the inlet connection portion 31 of the second exhaust gas purification device 3 while mixing.
The exhaust gas is uniformly introduced into the two SCR catalyst devices 5 by the diversion guide member 31b of the inlet connecting portion 31.
In each SCR catalyst device 5, the exhaust gas is reduced to nitrogen (N 2) and water (H 2 O) by the SCR catalyst 51.
The post-stage oxidation catalyst 52 oxidizes the ammonia slipped from the SCR catalyst device 5.
The purified exhaust gas is discharged from the second outlet chamber 54 to the atmosphere via the discharge connecting pipe 32.

With such a structure, since the axis CL2 of each SCR catalyst device 5 of the second exhaust gas purification device 3 is disposed so as to be perpendicular to the axis CL1 of the first exhaust gas device, the second exhaust gas purification device. Therefore, the overall size of the exhaust gas purifying apparatus 1 can be made compact, and mounting on a vehicle and reduction in size and weight of the entire apparatus can be achieved.
Furthermore, by arranging the two SCR catalyst devices 5 of the second exhaust gas purification device 3 in parallel, the passage cross-sectional area when the exhaust gas passes through the SCR catalyst device 5 becomes large, so that the SCR catalyst 51 and the exhaust gas The contact area becomes large, the performance of the SCR catalyst device 5 can be utilized to the maximum, the volume of the SCR catalyst 51 can be made the minimum necessary size, and the cost of the catalyst can be reduced.
Further, by arranging the SCR catalyst device 5 of the second exhaust gas purification device 3 in parallel, the flow resistance of the exhaust gas can be lowered compared to the case where they are arranged in series, the exhaust resistance of the internal combustion engine is reduced, and the output is reduced. This will improve fuel efficiency.

(Second Embodiment)
This embodiment is the same as the first embodiment except that the two SCR catalyst devices 5 are displaced vertically in a side view from the outside of the vehicle.
Therefore, the same components are denoted by the same reference numerals and description thereof is omitted.

FIG. 4 is a side view of the exhaust gas purification device 10 as viewed from the outside of the vehicle.
The exhaust gas purification device 10 connects the first exhaust gas purification device 2, the second exhaust gas purification device 3, the inlet connection portion 31 of the second exhaust gas purification device 3, and the first outlet chamber 24 of the first exhaust gas purification device 2. A communication pipe 7, a urea water addition nozzle 9, and an exhaust pipe 35 are provided.
The communication pipe 7 connected to the first outlet chamber 24 of the first exhaust gas purification device 2 is connected to the inlet connection portions 31 of the two SCR catalyst devices 5 of the second exhaust gas purification device 3.

The two SCR catalyst devices 5 are centered on the opening center CP1 of the inlet connecting portion 31. The SCR catalyst device 5 on the vehicle front side is lowered L6 downward, and the SCR catalyst device 5 on the vehicle rear side is raised L6 upward. Arranged in shape.
As a result, the size of L5 in the vehicle front-rear direction can be reduced on one side, the mountability on the vehicle is increased, and the vehicle can be easily mounted on a vehicle having a short wheelbase (WB).
In the second embodiment, the L3 dimension is maintained between the axis lines CL of the two SCR catalysts 5.
However, for example, the diversion guide portion 35b (two-dot chain line in FIG. 5) is tangent to the cylindrical second inlet chamber 53 so that the exhaust gas guided by the diversion guide portion 31b does not concentrate on the SCR catalyst 5. It is possible to further reduce the size of the vehicle in the front-rear direction by reducing the L3 size by forming the guide in the direction.

(Third embodiment)
The present embodiment is the same as the first embodiment except that the exhaust pipes from the second outlet chambers 54 and 54 of the two SCR catalyst devices 5 are made independent of each other.
Therefore, the description of the same part is omitted.

FIG. 5 is a plan view of the exhaust gas purification device 20.
The exhaust gas purification device 20 connects the first exhaust gas purification device 2, the second exhaust gas purification device 3, the inlet connection portion 31 of the second exhaust gas purification device 3, and the first outlet chamber 24 of the first exhaust gas purification device 2. The communication pipe 7, the urea water addition nozzle 9, and exhaust pipes 37 and 38 connected to the second outlet chambers 54 and 54 of the SCR catalyst device 5 are provided.

One exhaust pipe 37 is connected to the second outlet chamber 54 of the SCR catalyst device 5 disposed on the rear side in the vehicle longitudinal direction of the second exhaust gas purification device 3.
The other exhaust pipe 38 is connected to the second outlet chamber 54 of the SCR catalyst device 5 disposed on the front side in the vehicle front-rear direction of the second exhaust gas purification device 3.
Each of the exhaust pipes 37 and 38 is configured to discharge exhaust gas to the atmosphere independently.
By using the exhaust pipes 37 and 38 as independent exhaust pipes, when the exhaust pipes 37 and 38 flow out from the second outlet chambers 54 and 54 to the exhaust pipes 37 and 38, the exhaust interference due to the other exhaust pulsating flow is prevented. An increase in resistance can be suppressed.
Suppressing the flow resistance of the exhaust gas improves the output by reducing the exhaust resistance of the internal combustion engine and improves the fuel consumption.

  The present invention relates to an exhaust gas purification device for an internal combustion engine, and can be applied particularly to an exhaust gas purification device that removes nitrogen oxides contained in exhaust gas.

DESCRIPTION OF SYMBOLS 1, 10, 20 Exhaust gas purification apparatus 2 1st exhaust gas purification apparatus 3 2nd exhaust gas purification apparatus 5 SCR catalyst apparatus 7 Communication pipe 8 Chassis frame 9 Urea water addition nozzle (reducing agent addition nozzle)
21 Pre-stage oxidation catalyst 22 DPF (diesel particulate filter)
23 1st entrance chamber (exhaust gas inflow part of 1st exhaust gas purification apparatus)
24 1st exit chamber (exhaust gas outflow part of 1st exhaust gas purification apparatus)
31 Entrance connection part (connection part)
31a, 32a Top part 31b, 35b Splitting guide part 32 Discharge connection part 32b Discharge guide part 35, 37, 38 Exhaust pipe 51 SCR catalyst (selective reduction type SCR catalyst)
52 Second-stage oxidation catalyst 53 Second inlet chamber (exhaust gas inflow part of second exhaust gas purification device)
54 2nd exit chamber (exhaust gas outflow part of 2nd exhaust gas purification apparatus)

Claims (7)

An exhaust gas purification device interposed in an exhaust system passage of an internal combustion engine,
A first exhaust gas purification device in which a front stage oxidation catalyst and a diesel particulate filter are arranged in series on the downstream side of the front stage oxidation catalyst, and an axis extending in the vehicle longitudinal direction;
A plurality of SCRs arranged downstream of the first exhaust gas purification device in the exhaust system and having a selective reduction SCR catalyst and a downstream oxidation catalyst arranged in series downstream of the selective reduction SCR catalyst. The catalyst devices are arranged in parallel, and the axes of the SCR catalyst devices arranged in parallel are arranged substantially perpendicular to the axis of the first exhaust gas purification device, and the plurality of SCR catalyst devices A second exhaust gas purification device having an inlet connection portion for connecting the respective exhaust gas inflow portions;
A communication pipe for connecting the exhaust gas outflow part of the first exhaust gas purification device and the inlet connection part to circulate the exhaust gas inside;
An exhaust gas purification apparatus comprising: a reducing agent addition nozzle disposed in the communication pipe and spraying a reducing agent on the exhaust gas flowing in the communication pipe.   The reducing agent addition nozzle is disposed at an end portion of the communication pipe, which is a joint portion between the outer peripheral wall of the outflow portion of the first exhaust gas purification device and the communication pipe. Item 1. An exhaust gas purifying apparatus according to Item 1.   The flow dividing guide portion for allowing the exhaust gas from the communication pipe to uniformly flow into the exhaust gas inflow portion of each of the plurality of SCR catalyst devices is disposed in the inlet connection portion. The exhaust gas purification apparatus according to any one of the above.   The plurality of SCR catalyst devices and the communication pipes arranged in parallel are arranged so that the outer dimension in the vehicle front-rear direction is substantially the same as the front-rear dimension of the first exhaust gas purification device in plan view when mounted on the vehicle. The exhaust gas purification device according to any one of claims 1 to 3, wherein the exhaust gas purification device is provided.   The exhaust gas purification device according to any one of claims 1 to 4, wherein the plurality of SCR catalyst devices arranged in parallel are displaced in the vehicle vertical direction. The vehicle includes a chassis frame having a pair of left and right side frames extending in the vehicle front-rear direction and having an interval in the vehicle width direction at the center in the vehicle width direction,
6. The first exhaust gas purification device is disposed between the pair of left and right side frames, and the second exhaust gas purification device is disposed outside the side frame in the vehicle width direction. The exhaust gas purification apparatus according to any one of the above. The exhaust gas purifying apparatus according to any one of claims 1 to 6, wherein an exhaust gas pipe is provided in each exhaust gas outflow portion of each of the plurality of SCR catalyst devices.

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